A device used to convert a non-electrical quantity into an electrical signal is called :
Transducer
A transducer converts energy from one form to another, and in instrumentation that means turning a physical quantity into an electrical signal — option 3.
The word itself is the definition: from the Latin transducere, to lead across — across a boundary between physical domains.
| Transducer | Converts | Principle |
|---|---|---|
| Thermocouple | Temperature to voltage | Seebeck effect |
| Strain gauge | Strain to resistance | Geometry and piezoresistance |
| LVDT | Displacement to voltage | Mutual inductance |
| Piezoelectric crystal | Force to charge | Piezoelectric effect |
| Photodiode | Light to current | Photogeneration |
Why the other three are excluded — and it is the same reason each time. All of them are electrical-to-electrical devices: a transformer changes a voltage level, an oscillator generates a waveform from a DC supply, and an inverter converts DC to AC. None crosses the boundary between a physical quantity and an electrical one, which is exactly what the question asks for.
A distinction worth making. A sensor is strictly the element that responds to the measurand, while a transducer is the sensor together with whatever converts that response into a usable signal. In everyday use the words are interchangeable, but the difference matters when reading a data sheet: a bare thermistor is a sensor, and a thermistor with its bridge and amplifier packaged together is a transducer with a calibrated output.
Transducers also run the other way. An actuator — a loudspeaker, a solenoid, a motor, a piezoelectric buzzer — converts an electrical signal back into a physical quantity, and is properly an output transducer. Some devices work in both directions: a loudspeaker used in reverse is a microphone, and a piezoelectric crystal both generates a voltage when squeezed and deforms when a voltage is applied, which is why the same element serves as both transmitter and receiver in an ultrasonic system.
Why the conversion to electrical form is worth making at all : electrical signals can be amplified, filtered, transmitted over distance, digitised and recorded, none of which is convenient for a mechanical or thermal quantity in its original form.
Hence, the device is a transducer.
Similar Questions
Which of the following statements are correct ?
A. Hygrometer measures the value of humidity directly
B. Hygrometer measures the value of humidity indirectly
C. Wien's bridge is used to measure the frequency of the signal
D. Wien's bridge is used to measure the amplitude of the signal
E. Bimetallic strip is a thermal expansion detector.
Choose the most appropriate answer from the options given below :
Which of the following statements are correct
A. Megnetostrictive transducer operation depends on the change of permeability of magnetic material is when strained.
B. Potentiometer is an active transducer.
C. Turbine flow meters are volumetric flow meters
D. Any metal can be thermistor.
E. Thermocouples are used in high accuracy measurements.
Choose the most appropriate answer from the options given below :
Match List I with List II
LIST I LIST II A. Stroboscope I. Changes its electrical resistance with temperature B. Bolometer II. Generate thermoelectric emf C. Thermocouple III. Changes pressure to displacement D. Diaphragm IV. For measurement of rotary motion Choose the correct answer from the options given below:
Match the following lists :
List – I List – II a. Electromechanical Device i. Seismic Device b. Optical Device ii. Piezo-electric c. Gyroscopic device iii. Interferometers d. Absolute motion device iv. Aerospace vehicle Choose the correct answer from the codes given below:
Consider the following transducers or transducer systems :
(a) Float elements
(b) Seismic system
(c) Gyroscope
Arrange the above transducers/systems in decreasing order of the availability of possible number of output signals.
Consider the following statements associated with electrical and electronic transducers
A. Little power is consumed by transducer
B. Mass intertia effects are not minimized
C. The response time is small
D. Transmission and processing the signal for the purpose of measurement are easier.
Choose the correct answer from the options given below:
Match List I with List II
LIST I LIST II A. Relative error I. The ability of tde device to give identical O/P when repeated measurements are made witd tde same I/P signal B. Precision II. The ratio of difference between measured value and tde true value to tde true value of tde measurand C. Caliberation III. The smallest increment in measure tdat can be detected witd certainity by tde instrument D. Resolution IV. The process of making adjustments or tde scale so tdat tde instrument reading conform to an accepted standard. Choose the correct answer from the options given below:
The fundamental law that is used in temperature measurement is known as
Assertion (A) : Normally, some standard signal conditioner and display devices are used with a transducer, unless they are custom-built to suit the requirements of the transducers.
Reason (R) : A transducer is a device which receives energy in one form and transfer it to a convenient form.
Select your answer using the codes given below :
Which of the following transducers are not linear ?
i. thermistor
ii. thermocouple
iii. IC sensor
Important Questions from Basics of Transducers
Which of the following can act as an inverse transducer?
For transducers, following statements are given:
(A) An optical interferometer is useful for measuring extremely small motions
(B) The damping ratio of a seismic instrument should be low for good dynamic performance
(C) A rate gyro is a relative motion measuring device
(D) A pneumatic motion transducer is non-linear over a wide range of motion
(E) A piezoelectric accelerometer can only be used for static motion measurement
Choose the correct answer from the options given below:
Choose the INCORRECT statement with respect to the use of electrical transducers.
Consider the following transducers:
1. LVDT
2. Piezoelectric
3. Thermocouple
4. Photovoltaic cell
5. Strain gauge
Which of these are active transducers?
Under which condition, Transducers must operate?
